Audio software mixer.

media/audio/audio_output_proxy.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_AUDIO_AUDIO_OUTPUT_PROXY_H_
 #define MEDIA_AUDIO_AUDIO_OUTPUT_PROXY_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
 #include "base/threading/non_thread_safe.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 
 class AudioOutputDispatcher;
 
 // AudioOutputProxy is an audio otput stream that uses resources more
 // efficiently than a regular audio output stream: it opens audio
 // device only when sound is playing, i.e. between Start() and Stop()
 // (there is still one physical stream per each audio output proxy in
 // playing state).
 //
 // AudioOutputProxy uses AudioOutputDispatcher to open and close
 // physical output streams.
 class MEDIA_EXPORT AudioOutputProxy
   : public AudioOutputStream,
     public NON_EXPORTED_BASE(base::NonThreadSafe) {
  public:
   // Caller keeps ownership of |dispatcher|.
   explicit AudioOutputProxy(AudioOutputDispatcher* dispatcher);
 
+  // Accessors.
+  AudioSourceCallback* audio_source_callback() const {
+    return audio_source_callback_;
+  }
+
+  int pending_bytes() const {
+    return pending_bytes_;
+  }
+
+  void set_pending_bytes(int pending_bytes) {
+    pending_bytes_ = pending_bytes;
+  }
+
   // AudioOutputStream interface.
   virtual bool Open() OVERRIDE;
   virtual void Start(AudioSourceCallback* callback) OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void SetVolume(double volume) OVERRIDE;
   virtual void GetVolume(double* volume) OVERRIDE;
   virtual void Close() OVERRIDE;
 
  private:
   enum State {
@@ skipping 10 matching lines @@
   State state_;
 
   // The actual audio stream. Must be set to NULL in any state other
   // than kPlaying.
   AudioOutputStream* physical_stream_;
 
   // Need to save volume here, so that we can restore it in case the stream
   // is stopped, and then started again.
   double volume_;
 
+  // Callback.
+  AudioSourceCallback* audio_source_callback_;
+
+  // Lock protecting |volume_| -- we can read it in the hardware audio thread.
+  base::Lock lock_;
+
+  // Number of pending bytes in the buffer.
+  // Initialized in Start() and after that accessed only in the hardware thread.
+  int pending_bytes_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioOutputProxy);
 };
 
 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_PROXY_H_